How to make a whiff of steam rising off a mug of coffee?
I did it by using an Emission shader for the volume.  I mixed with the given quick smoke setup that uses Volume Scatter and Volume Absorption, but the mix is so low for them I suspect that I could leave them out.  I also animated the density from 1 to 0. (Stuff is grayed out in the domain's settings because I baked it.)  I changed things like the Vorticity and Dissolve time, and Noise Method and Strength. My problem was getting the steam to be white instead of gray. Maybe if I got rid of the Volume Absorption I wouldn't need the Emission?  It doesn't look quite right since the steam is lighting up the inside of the cup.

animation (it's still rendering and needs about 30 more frames for the full 70 frames.)